Controller area networks are used in a number of industries, such as the automotive industries, for providing connections between simple industrial devices, such as sensors or actuators, and higher-level devices, such as an electronic control module (ECM). A standard implementation of an isolated CAN data link is described in “Volume I: DeviceNet Communication Model and Protocol,” Open DeviceNet Vendor Association, Inc., Release 2.0, 1997, p. 1—1. A standard CAN data link may include a CAN controller, a transceiver, an isolation module, and an isolated power supply. The CAN controller includes a device that handles incoming and outgoing CAN messages. The CAN controller may be part of a microprocessor or peripheral. The transceiver includes a bus driver and/or receiver and is connected on one side to the CAN and on the other side to the CAN controller via the isolation module. The isolation module isolates control logic (such as the CAN controller) from noise, voltage surges, and spikes. The isolation module typically includes optocouplers, which may use diodes. The isolated power supply provides voltage to both the transceiver and the isolation module.
The use of optocouplers for electrical isolation is relatively expensive. Nonetheless, the standard implementation of the isolated CAN data link, using optocouplers for isolation, can be effective in certain applications. There are, however, situations when the standard implementation is insufficient. In particular, the conventional CAN data link may become unreliable at high heats because the optocoupler malfunctions. Most optocouplers cannot function reliably at higher operating temperatures, such as 120° C. In automotive applications, temperatures of up to 120° C. may occur, for example, due to mud build-up or other factors. In order to counter this problem, the industry standard currently uses hermetic sealing of the optocouplers. Another option is to use fuel coolant as a heat sink. Both of these methods are, however, expensive to implement.
Thus, the prior art does not provide an inexpensive isolation design that can be utilized in all working environments. The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.